The present invention relates to systems that control levels of liquids in reservoirs. Specifically this invention relates to liquid level sensing and control systems for wastewater systems.
It is often desirable to know information about liquid levels in tanks. Determining liquid levels and controlling liquid levels in reservoirs, such as in sewage tanks, wells, water cisterns or tanks, and other liquid systems and storage vessels, whether enclosed or open and exposed to the environment, has been done in a number of ways. For example, in tanks that are visually accessible, an operator may periodically take visual readings of the liquid level.
Visual readings, however, are often not desirable in systems where an automatic response is required when the liquid level reaches a certain threshold. In such cases the activation of a pump or valve may be necessary to move more liquid into the tanks or to discharge liquid from the tank. In systems where visual readings are not available or when an immediate response is required, control systems are typically employed that are responsive to a liquid level indication. Such control systems may illuminate a light on an indicator panel representing the liquid level and/or trip an audible alarm to notify a human operator that corrective action is required.
Examples of liquid level sensing devices for use with wastewater reservoirs or other liquid holding vessels or tanks are discussed in U.S. Pat. No. 6,595,051 of Jul. 22, 2003; U.S. Pat. No. 6,443,005 of Sep. 3, 2002; U.S. Pat. No. 7,075,443 of Jul. 11, 2006; and U.S. Pat. No. 7,224,283 of May 29, 2007, which are all hereby incorporated by reference herein.